Spoked wheel for a bicycle

ABSTRACT

A spoked wheel for a bicycle is described herein, comprising a hub, a rim and a plurality of spokes that connect the hub to the rim. The spokes comprise a first set of spokes arranged on one side of the wheel, made up of spokes connected to a first portion of the hub, and a second set of spokes arranged on the other side of the wheel, made up of spokes connected to a second portion of the hub. The second hub portion is set at an axial distance from said first portion. The spokes of the first set are grouped together into pairs set at angular distances apart from one another with the spokes of each pair that have their outer ends set close to one another.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.10/812,140, filed Mar. 29, 2004, which is incorporated by reference asif fully set forth.

FIELD OF THE INVENTION

The present invention relates to a spoked wheel for a bicycle,particularly one that comprises a hub, a rim, and a plurality of spokesthat connect the hub to the rim. The spokes comprise a first set ofspokes arranged on one side of the wheel, made up of spokes connected toa first portion of the hub, and a second set of spokes connected to asecond portion of the hub set at an axial distance from said firstportion and are arranged on the other side of the wheel.

BACKGROUND

Recent studies and research have been aimed at identifying newconfigurations of spoked wheels for bicycles leading to betterperformances of the wheel, as well as creating an original andinnovative aesthetic effect.

Research in the field of spoked wheels for road racing bicycles has beendirected to identifying increasingly important solutions that optimallyreduce weight and increase the static and dynamic stability of thewheel. Research has also been directed to increasing structural strengthand reduction in the risks of failure of the spokes of the wheel.

The spokes of road racing wheels make a substantial contribution tomaintaining the static and dynamic stability of the bicycle wheel.Particularly in rear wheels, the spokes are responsible for transmittingthe driving torque from the hub to the rim of the wheel. The drivingtorque transmission should occur with the maximum possible efficiency,and with minimum deformations, so as not to dissipate the energy exertedon the pedals by a cyclist. Finally, the desired results should beachieved with the minimum weight possible and without introducing riskfactors for failure in the spokes. From this standpoint, a particularlycritical factor is the tensioning of the spokes during wheel assembly.One of the purposes of said tensioning is to guarantee that the rim willalways remain “centered” or “true”, i.e., it will not shift away from amedian plane of the wheel orthogonal to the axis of the hub andequidistant from the ends of the hub itself. Thus, the spokes of atypical spoked wheel include a first set of spokes on one side of thewheel, connected to a first hub portion, and a second set of spokes onthe other side of the wheel, connected to a second hub portion. Thesecond hub portion being set at an axial distance from the firstportion. Consequently, the spokes on the two sides of the wheel have aninclination or camber angle with respect to the median plane of thewheel. This inclination causes the spoke tensioning to give rise tocomponents of force in a direction parallel to the axis of the wheel.Balancing of the components of force keeps the rim in the centered ortrue condition. Spoke tensioning is most critical in wheels where thespokes on the two sides of the wheel present different camber angles.This is typically the case for spokes of the rear wheel. A rear wheelhub carries at one end, a sprocket cassette. The spokes set on the sideof the wheel bearing the sprocket cassette have camber angles orinclinations that are considerably smaller than the camber angles orinclinations of the spokes on the other side. Obviously, the spokes withsmaller inclinations must be tensioned more than the spokes on the otherside in order to guarantee the centered position of the rim. This highertensioning gives rise to a greater risk of failure of the individualspoke itself. Different spoke camber angles on the two sides of thewheel is not unique to rear wheels. It exists in general in any wheel,whether rear or front, in which the hub is partially occupied, forinstance, by the disk of a disk brake.

SUMMARY

The present invention provides a spoked wheel comprising a rim, a hubhaving a first anchoring portion and a second anchoring portion foranchoring spokes and a plurality of spokes that connect the hub to therim. A first set of spokes are connected to the first anchoring portionand a second set of spokes is connected to the second anchoring portion.The wheel comprises at least two spokes wherein at least one of the twosets of spokes are grouped together to form a pair that has no spoke ofthe other set interposed. Further advantageous characteristics of thespoked wheel according to the invention are specified below.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will emerge fromthe following description with reference to the appended drawings, whichare provided purely by way of non-limiting example and in which:

FIG. 1 illustrates a spoked wheel for a bicycle according to the priorart, viewed in the direction of the axis of the wheel;

FIG. 2 illustrates a first embodiment of the wheel according to theinvention, viewed in the direction of the axis of the wheel;

FIG. 3 is a perspective view, of a detail of the wheel illustrated inFIG. 2;

FIG. 4 illustrates a second embodiment of the wheel according to theinvention, viewed in the direction of the axis of the wheel;

FIG. 5 is a perspective view, of a detail of the wheel of FIG. 4;

FIG. 6 is a sectional view used for illustrating some advantages of theinvention with respect to the prior art;

FIG. 7 is a partial perspective view of an alternate embodiment of thewheel according to the invention;

FIG. 8 illustrates a further alternate embodiment of the wheel accordingto the invention;

FIG. 9 is an alternate embodiment of the wheel according to theinvention; and

FIG. 10 is a further alternate embodiment of the wheel of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, illustrated therein is a conventional bicyclewheel, designated as a whole by the reference number 1. The wheelcomprises a hub 2, a rim 3 on which a tire 4 can be mounted, a pluralityof spokes A belonging to a first set, which connect one side 2 a of thehub 2 to the rim 3, and a plurality of spokes B belonging to a secondset, which connect the other side 2 b of the hub 2 to the rim 3. Asviewed in the direction of the wheels axis, spokes A of the first setalternate with the spokes B of the second set. In a conventional wheel,the spokes are uniformly distributed along the rim, and the distance, orpitch, between two adjacent spokes that belong to two different sets, isdesignated by P. It is evident that the pitch P depends upon the totalnumber of spokes that form the wheel and that it is given by C/N, whereC is the internal circumference of the rim and N is the total number ofspokes of the wheel.

Alternatively, FIGS. 2 to 7, and 9 to 10, illustrate alternateembodiments of the wheel according to the invention, considering thatother and different embodiments are possible, all of which are comprisedwithin the scope of the present invention.

In said figures, the parts that are in common or correspond to thoseillustrated in FIG. 1 are designated by the same reference numbers.

The present description will not go into any detail of the structure andconformation of the hub 2 and of the rim 3, since these elements areknown and the structure of these components alone does not fall withinthe scope of the present invention. Likewise, the mechanical fasteningor physical way in which each spoke is connected, at one end, to the hub2 and, at the other end, to the rim 3, is not illustrated in detail. Anyknown technique suitable for this purpose can be used. The eliminationof said constructional details from the drawings makes the latter easierand faster to understand the invention.

FIGS. 2 and 3 refer to the use of the invention with a rear bicyclewheel, in which a sprocket cassette 5 is associated with the hub 2. Thiscassette comprises a plurality of sprockets designed to selectivelyengage the drive chain of the bicycle in a conventional way.

The spokes that connect the hub to the rim of the wheel according to theinvention are arranged in first and second sets, on the two oppositesides of the wheel. The spokes of the first set, designated by A, areconnected to one end 2 a of the hub 2 adjacent to the sprocket cassette5, and the spokes of the second set, designated by B, are connected to aportion 2 b of the hub 2, set at an axial distance from the end 2 a.

In all the embodiments of the wheel according to the invention, thespokes A of the first set are grouped together into a plurality of pairsC, which, in the example illustrated, are set at an equal distance onefrom the other. FIG. 2 shows five pairs C of spokes A, but the number ofsaid pairs C may vary widely, for instance between a minimum of fourpairs and a maximum of fourteen pairs.

By “pair of spokes C” is meant that, contrary to the traditional wheelof FIG. 1, between two spokes belonging to the same set, specificallybetween two spokes A, no spokes are interposed that belong to the otherset, in this case spokes B. Furthermore, the spokes of each pair C arealso brought close together, i.e., the distance L between the outer endsof the two spokes A of each pair C, or between the points of attachmentto the rim 3, is smaller than the pitch P of a conventional wheel havingthe same total number of spokes, where P is given by C/N, C being theinternal circumference of the rim and N being the total number of spokesof the wheel. In one preferred embodiment, the distance L between spokesA of pair C is less than or equal to 60% of pitch P. In a secondpreferred embodiment, the distance L is equal to or less than 40% ofsaid pitch P, and in a particularly preferred solution, said distance isequal to or less than 25% of said pitch P.

In another embodiment, illustrated in FIG. 8, in a rim having asufficient width, spokes A of the pair C may be connected to the rimsubstantially on the same point, by reducing the distance L between thetwo spokes A of the pair C substantially to zero. In a furtherembodiment illustrated in FIG. 7, spokes A of each pair C may convergein the same point of the rim, by means of connection element D providedwith a connection means that makes it possible to simultaneously tensionspokes A.

By the coupling of spokes A, each pair C of spokes A becomesstructurally equivalent to a single spoke of a larger cross sectionwithout, however, increasing weight. This effect is further improved bythe close coupling of the two spokes.

The distance L between the two spokes of the pair C is chosen so as tocause the tensile stress and the compressive stress (meant as reductionof the initial assembly tensile stress), transmitted simultaneously fromthe hub of the rear wheel (when the cyclist exerts force on the pedals)respectively to the two spokes of each pair C, generates locally, on theportion of the rim to which the spokes are connected, a much smallermoment than the one that would be generated with a traditional spokingand, namely, almost negligible, with a consequent low stressing of therim itself.

In the example illustrated in FIG. 7, spokes A of each pair C originatefrom two diametrically opposite points of the hub. Spokes A convergewith respect to one another towards the rim, according to two directionstangential to the axis of the hub, until they reach a distance apart attheir outer ends that is smaller than the diameter of the hub and isconsiderably smaller than the distance between adjacent pairs C.

The aforesaid arrangement is particularly suited to a rear wheel. In apreferred embodiment, the number of pairs C of spokes A is equal to thenumber of spokes B. Therefore, the rear wheel has twice the number ofspokes on the side of the spokes A, i.e., the side of the wheel on whichthe sprockets are arranged, than the number of spokes B on the oppositeside.

This arrangement leads to important advantages from the point of view ofstructural strength of the wheel. In particular, the spokes' resistanceto failure is enhanced and will be discussed below with reference toFIG. 6. This figure is a sectional view, corresponding to a view in theplane containing the axis of the wheel, which also illustrates the forkof the bicycle frame on which the wheel is mounted. The view of FIG. 6is a hypothetical view, since it shows spoke B on the left-hand side ofthe wheel and a pair of spokes A (only one of which can be seen) on theright-hand side of the wheel, as if these spokes were in a common plane,whereas, in reality, they are in different planes.

When in use with a rear wheel, as seen in FIG. 6, the presence of thesprocket cassette 5 at one end of the hub 2 indicates that the spokes Aset on that side of the hub will have an inclination α with respect tothe median plane M of the wheel that is considerably smaller than theinclination β with respect to the median plane M of the spokes B. Themedian plane M is defined as the plane orthogonal to the axis X of thehub that is substantially equidistant from the ends of the hub 2.

By convention, each spoke of the spoked wheel is mounted and appliedwith a given tensile force. In FIG. 6, T_(A) and T_(B) designate thecomponents of tensile forces applied to the two-spoke set on theopposite sides of the wheel. The components of the two forces (T_(A),T_(B)) in a direction parallel to the axis X of the wheel are generallydesignated by T_(AO) and T_(BO) in FIG. 6.

In conventional wheels having an equal number of spokes on the two sidesof the wheel, in order for horizontal components T_(AO) and T_(BO) to bebalanced with one another, so as to keep the rim 3 in the vertical planeM, it is necessary for the tensile force T_(A) to be much higher thanthe tensile force T_(B) due to its smaller inclination. To be precise,the ratio between the tensile force T_(A) and the tensile force T_(B)(of course always considering the tensile forces in the plane of FIG. 6)must be substantially equal to and opposite to the ratio of the sines ofthe angles of inclination α and β. This condition applies, in theconventional wheel, to each pair of spokes belonging to two differentsides of the wheel and also applies, as a whole, with reference to thetotal tensile forces of the spokes set on one side and on the other sideof the wheel. Furthermore, in conventional wheels, the tensioning of thespokes on the sprockets side is very high, with a consequent high riskof failure.

In view of the above, it is evident that the spoke arrangement accordingto the invention leads to important advantages. First of all, since thenumber of spokes A is twice the number of spokes B, the tensile forceT_(A) of each spoke A is substantially smaller than that required by aconventional wheel. Particularly, for each spoke B, the are two spokesA, so that for each tensile force T_(B), there is a correspondingtensile force T_(A), that is the sum of two tensile forces T_(A1)+T_(A2)that the two spokes A of each pair apply as a whole to the rim 3. T_(A1)and T_(A2) are generally equal to one another, but could also bedifferent.

Furthermore, it is important to note that, in the case of a typical rearwheel, the ratio between the sine of β and the sine of α isapproximately of 2:1. Therefore, in the rim's balanced condition, eachspoke A may be tensioned with a tensile force that substantiallyapproaches that of each spoke B. In other words, when the components ofthe tensile forces of the spokes in radial planes containing the axis ofthe wheel are considered, all the spokes come to have tensile forcesthat are substantially equal to one another.

With reference to the sums of the tensile forces of the spokes on thetwo sides of the wheel, the balance condition of the tensile forces ofthe spokes in the direction of the axis of the wheel applies to thewheel as a whole.

The above advantages of the embodiment in FIGS. 2 and 3 namely, greaterstrength and resistance of the spokes, lower tensioning of the spokes onthe sprocket side, and lower risk of failure of the spokes are allobtained without weight increase. These advantages are achieved with arelatively uniform distribution of the points of spokes anchoring on therim. This uniform distribution provides optimal geometrical stability ofthe circular shape of the rim itself.

In addition to providing the substantial advantages discussed above, awheel having a different number of spokes between the two camber anglesas in this invention is particularly advantageous for a wheel which hasan equal number of spokes for both of the camber angles. Although thisis typically the case for a front wheel, an equal number of spokes forboth of the camber angles may also be used for a rear wheel.

An example of this embodiment is illustrated in FIGS. 4 and 5. In thecase of the embodiment of FIGS. 4 and 5, spokes B of the second set aregrouped into pairs, which are arranged at equal distances apart from oneanother and alternated angularly between spoke pairs A. In thisarrangement, the spokes on the two sides of the wheel are equal innumber.

Alternatively, it is possible to arrange both spokes A and spokes B inpairs on both sides of the wheel. The pairs on the two sides have thesame angular positions, so that in each rim area where the spokesattach, two pairs of spokes belonging, respectively, to the two sides ofthe wheel converge, see FIG. 9. It is also possible that on one or bothsides of the wheel, pairs of spokes alternate with single spokes, whichare also set on the same side, see FIG. 10.

As is evident from the foregoing description and from the appendeddrawings, the invention provides a new wheel arrangement with aninnovative technical solution and an original aesthetic appearance.

1. A bicycle wheel comprising: a hub having an axis (X) and first andsecond portions on different sides of a median plane (M) which isperpendicular to the axis (X); a rim; a plurality of spokes, arranged insets of spokes, connecting the hub to the rim; a first set of saidspokes connecting the first portion of the hub to the rim on a firstside of the median plane; and a second set of said spokes connecting thesecond portion of the hub to the rim on a second side of the medianplane, each set of said spokes arranged so that no spoke of the otherset is interposed and that the spokes on each side of the median planeproduce generally equal forces in opposite directions along the axis (X)that maintain the rim centered about the median plane.
 2. The wheel ofclaim 1, wherein the spokes of each group of spokes, viewed in thedirection of the wheel's axis, have an arrangement that is specular withrespect to a radial plane of symmetry.
 3. The wheel of claim 2, whereinin each set of spokes, the spokes connected to at least one of the twohub portions include a spoke which, when viewed in the direction of thewheel's axis, is set at the center between two sets, in said radialplane of symmetry.
 4. The wheel of claim 1, wherein spokes on the secondside of the median plane extend radially from the hub to the rim whenviewed along the axis.
 5. The wheel of claim 1, wherein the spokes ofthe first and second sets of spokes are arranged in pairs.
 6. The wheelof claim 5, wherein the spoke pairs of the first set are connected to ahub portion on the first side of the median plane and the spoke pairs ofthe second set are connected to a hub portion on the second side of themedian plane, said hub portions set at an axial distance apart.
 7. Thewheel of claim 5, wherein tensile forces of the spokes of each set ofspokes have components of force in the direction of the axis of thewheel and are substantially balanced with one another.
 8. The wheel ofclaim 6, wherein tensile forces of the spoke pairs connected to the hubportion on the first side of the median plane are substantially equal toone another.
 9. The wheel of claim 6, wherein the sum of tensile forcesof the spokes connected to the hub portion on the first side of themedian plane and tensile force of the spokes connected to the hubportion on the second side of the median plane have their tensile forcecomponents in a plane containing the axis of the wheel, and wherein thecomponents are in a ratio with respect to one another that issubstantially equal and inverse to the ratio of the sines of respectiveangles of inclination with respect to said median plane.
 10. The wheelof claim 4, wherein the wheel is a rear bicycle wheel and wherein thespokes are oriented with all of the radially extending spokes on thesame hub portion, so that one hub portion has twice the number of spokesthan the other hub portion.
 11. The wheel of claim 10, wherein the hubportion with twice the number of spokes than the other is the hub potioncorresponding to the end of the hub which accepts a sprocket cassette.12. The wheel of claim 1, wherein the spokes connecting the first hubportion to the rim and the spokes connecting the second hub portion tothe rim have identical angular positions.
 13. The wheel of claim 12,wherein the spokes converge at a point on the rim.
 14. The wheel ofclaim 1, wherein the spokes connecting the first hub portion to the rimand the spokes connecting the second hub portion to the rim arealternately arranged between spoke pairs and single spokes on the samehub portion.
 15. A bicycle wheel comprising: a hub having an axis andfirst and second portions situated on either side of a median planeperpendicular to the axis; a rim; a plurality of spokes that connect therim to the hub that are arranged in first and second sets, the spokes ofthe first set attached to the first hub portion and the spokes of thesecond set attached to the second hub portion; the spokes of the firstset being arranged in pairs evenly spaced apart on the rim.
 16. Thewheel of claim 15, wherein the spokes of the second set are individuallyarranged on the rim between two spoke pairs of the first set.
 17. Thewheel of claim 15, wherein the spokes of the second set are arranged inpairs on the rim between two spoke pairs of the first set.
 18. The wheelof claim 16, wherein the spokes of the first set converge at a point onthe rim.
 19. The wheel of claim 16, wherein the spokes of the second setextend radially from the hub to the rim when viewed along the axis.